CSS3 PIE is an HTC file that allows you to use standard CSS3 (plus vendor prefixes) to get features such as linear background gradients, rounded corners and drop-shadows in all browsers. HTC files are applied using a behavior in your CSS, which is IE-only, and does not validate.

#example1 {
	background: #d1c26c; /* Old browsers */
	background-image: -moz-linear-gradient(top, #d1c26c 0%, #e5e2b9 22%, #d1cd96 66%, #b5a75c 100%); /* FF3.6+ */
	background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#d1c26c), color-stop(22%,#e5e2b9), color-stop(66%,#d1cd96), color-stop(100%,#b5a75c)); /* Chrome,Safari4+ */
	background-image: -webkit-linear-gradient(top, #d1c26c 0%,#e5e2b9 22%,#d1cd96 66%,#b5a75c 100%); /* Chrome10+,Safari5.1+ */
	background-image: -o-linear-gradient(top, #d1c26c 0%,#e5e2b9 22%,#d1cd96 66%,#b5a75c 100%); /* Opera11.10+ */
	background-image: -ms-linear-gradient(top, #d1c26c 0%,#e5e2b9 22%,#d1cd96 66%,#b5a75c 100%); /* IE10+ */
	background-image: linear-gradient(top, #d1c26c 0%,#e5e2b9 22%,#d1cd96 66%,#b5a75c 100%); /* W3C */
}
html.lte9 #example1 {
	-pie-background: linear-gradient(top, #d1c26c 0%,#e5e2b9 22%,#d1cd96 66%,#b5a75c 100%); /* CSS3 PIE */
	behavior: url('../../wp-content/themes/practicalcss3/css3-pie.htc'); /* IE6-9 */
	zoom: 1; /* 'hasLayout' required for HTC method */
}